UK says ex-spy poisoned with Soviet-developed nerve agent

LONDON — The use of Russian-developed nerve agent Novichok to poison ex-spy Sergei Skripal and his daughter makes it “highly likely” that Russia was involved, British Prime Minister Theresa May said Monday.

Novichok refers to a class of nerve agents developed in the Soviet Union near the end of the Cold War. The agents were ostensibly created in an attempt to avoid the international chemical weapons treaty that had just been signed; any new substances wouldn’t be subject to past treaties.

Novichok behaves slightly differently than other nerve agents, with some reports that the class of substances is deadlier than similar chemicals like sarin or VX and harder to identify.

“Novichok agents significantly extend the range of possibility for nerve agents,” said Andrea Sella, a professor of inorganic chemistry at University College London. There are five known nerve agents, which are mostly colorless liquids that can kill within minutes, if ingested.

“With Novichok, you have the potential for a slower-release agent, which gives you much more control,” Sella said. “Using Novichok makes it pretty clear that it was likely Russia that was behind this.”

Gary Stephens, a pharmacology expert at the University of Reading, noted that the component ingredients of Novichok nerve agents aren’t on the banned list.

“It means the chemicals that are mixed to create it are much easier to